The present invention relates to self-sealing valves, and in particular, it relates to self-sealing valves for use in implantable devices.
In recent developments in inflatable prosthetic devices, it has been found desirable to progressively inflate the prosthetic device over a period of time. This has required the use of subcutaneous injection sites connected to the inflatable prosthetic device by a fill tube.
Implantable devices that are used both as a skin expander and a breast prosthesis have become increasingly popular. Initially, this type of expander/prosthesis is implanted in a deflated state in a pocket surgically made in the breast area. The device includes an inflatable chamber, and a subcutaneously implanted injection site which is connected to the inflatable chamber through a fill tube. The fill tube is connected to the inflatable chamber by a valve which has the ability to seal once the fill tube is pulled.
Once the expander/prosthesis is filled to a desired inflation level or the amount of skin expanded reaches a desired level, the fill tube is pulled out of the valve and is removed from its subcutaneous location along with the injection site. Upon removal the valve must seal and the expander now acts as a prosthesis. The key to such a device functioning properly is the ability of the valve to seal once the fill tube is removed, such that there is absolutely no leakage.
The prior art valves that have been used in such prostheses, although providing a seal, do not provide an absolute seal since some leakage can occur. It will be appreciated that although the leakage rate is slight, and not noticeable over a short period of time, any decrease in fluid volume in the prosthesis over several years is unacceptable.
A practical aspect of implantation of such devices is that from the time the device is manufactured to the time that the fill tube is pulled from the valve may be two years or more. It has been found that stresses are placed in the valve material which surrounds the fill tube to an extent that such material does not relax back to its original (closed) position and therefore does not provide an absolute seal once the fill tube is removed.
One type of valve that has been used is made of two sheets of silicone elastomer bonded together along edge portions to form a passage between the bonded edge portions. A fill tube is typically inserted within the passage. If the fill tube is in the passage for any length of time, the silicone rubber around the passage area is stressed, resulting in the valve not sealing adequately once the fill tube is removed. The passage becomes somewhat "set" over time and cannot return to its original position once the fill tube has been removed.
A curling self-sealing valve is described in Bell et al U.S. Pat. No. 4,662,883 entitled "Self-sealing Valve for Fluid Fillable Device" that provides a seal by curling along the longitudinal axis of the fill tube passage.
Another self-sealing valve for fluid fillable article is disclosed in the Fogerty et al U.S Pat. No. 4,775,379. The valve in the Fogerty et al patent has a passage portion which is flanked on opposing sides by first and second portions of elastomeric material. The passage portion is in a stretched state relative to the first and second portions so that the passage portion curls along the passage when the fill tube is removed.
The Boone patent describes an implantable mammary prosthesis including an inflatable shell and a filling stem. At the point of introduction of the stem into the shell, the stem passes through a capsule of sealing gel. After implantation and inflation, the stem is withdrawn either wholly or partially and gel in the capsule seals the stem outlet against leakage of the inflating fluid.
A number of other patents directed to prosthetic inflatable devices show valves which are constructed of two sheets of silicone elastomer bonded together along two edges to form a passage. None of the valves illustrated in the immediately below-listed patents are constructed to avoid the passage being permanently deformed due to the stress caused by the fill tube being present in the passage over a long period of time:
______________________________________ Inventor Pat. No. ______________________________________ Hyans U.S. 4,459,318 Bejarano U.S. 4,263,682 Cox, Jr. U.S. 4,178,643 Koneke et al U.S. 3,852,833 McGhan et al U.S. 3,852,832 Valliancourt et al 3,565,078 Krueger 2,697,229 ______________________________________
Other patents describe yet different valve arrangements in breast prosthesis:
______________________________________ Inventor U.S. Pat. No. ______________________________________ Cowen 4,433,440 Boone 3,600,718 Leo et al 2,516,129 ______________________________________
A number of other patents show inflatable devices other than prosthetic devices that include a variety of valving arrangements for the introduction of air. However, these valves in the immediately below-listed patents are also not designed for the retention of a fill tube for a long period of time.
______________________________________ Inventor Pat. No. ______________________________________ Kampa U.S. 3,584,671 Mirando U.S. 3,523,563 Mondano U.S. 3,410,300 Nicholls U.S. 3,204,959 Siedow U.S. 2,933,120 Blaszkowski et al U.S. 2,826,523 Orms U.S. 2,795,425 Andrews U.S. 2,700,980 Andrews U.S. 2,568,976 Riddell U.S. 2,142,414 Goldsmith et al U.S. 1,551,099 Gregory U.S. 1,008,641 Brookes U.S. 564,502 Ingram U.K. 9,698 Tomkins French 719,244 ______________________________________